The present invention relates to a process for preparing low-foaming nonionic surfactants and more particularly to a process for preparing ether-capped poly(oxyalkylated) alcohol surfactants which have superior spotting and filming benefits in dishwashing and hard surface cleaning applications, as well as suds suppression in detergent compositions.
Dishwashing and hard surface cleaning, in particular automatic dishwashing in domestic appliances, is an art very different from fabric laundering. Domestic fabric laundering is normally done in purpose-built machines having a tumbling action. These are very different from spray-action domestic automatic dishwashing appliances. The spray action in the latter tends to cause foam. Foam can easily overflow the low sills of domestic dishwashers and slow down the spray action, which in turn reduces the cleaning action. Thus in the distinct field of domestic machine dishwashing, the use of common foam-producing laundry detergent surfactants is normally restricted. These aspects are but a brief illustration of the unique formulation constraints in the domestic dishwashing and hard surface cleaning fields.
One solution to this foaming problem has been to include a suds suppressor, typically a silicone suds suppressor. However, this solution while it works to a certain extent in fabric laundering compositions, fails in domestic dishwashers. The high shear forces involved in domestic dishwashers breaks down the silicone suds suppressors, so any suds suppressors present at the start of the wash is gone before the end. The silicone suds suppressors are not robust enough to survive in the environment of a domestic dishwasher. Even in laundry applications, while less shear than that in a domestic dishwasher, there is still a drop off in suds suppression towards the end of the washing cycle, because of the break down of the silicone suds suppressor. One alternative would be increase the amount of silicone suds suppressor present, however the cost of silicone suds suppressors and the fact that they have a tendency to redeposit on hydrophobic surfaces, such as plastic, makes this an undesirable solution. There remains today the need for a viable and cost effective alternative to silicone suds suppressor suitable for use in automatic dishwashers as well as laundry washing machines.
On account of the foregoing technical constraints as well as consumer needs and demands, these compositions are undergoing continual change and improvement. Moreover environmental factors such as the restriction of phosphate, the desirability of providing ever-better cleaning results with less product, providing less thermal energy, and less water to assist the washing process, have all driven the need for improved compositions.
However, many compositions heretofore proposed for cleaning dishware and hard surfaces have had aesthetic and technical disadvantages, not the least of which is undesirable spots and films on the cleaned surfaces. These undesirable spots and films may be caused by redeposition of soils and cleaning agents such as surfactants which have a low solubility in water. In addition, there continues to be a need for better cleaning, especially for reduction of spots and films and in some cases removal of greasy soils. This need is driven by consumer demand for improving performance from the cleaning compositions spotting and filming benefits and on hard to remove greasy soils.
Accordingly, the need remains for low-foaming surfactants which can deliver improved spotting and filming reduction benefits while providing greasy soil removal, as well as providing suds suppression which is robust enough to survive the washing environment in which it is deployed.
U.S. Pat. No. 4,272,394, issued Jun. 9, 1981, U.S. Pat. No. 5,294, 365, issued Mar. 15, 1994 U.S. Pat. No. 4,248,729, issued Feb. 3, 1981; U.S. Pat. No. 4,284,532, issued Aug. 18, 1981; U.S. Pat. No. 4,627,927, issued Dec. 9, 1986; U.S. Pat. No. 4,790,856, issued Dec. 13, 1988; U.S. Pat. No. 4,804,492, issued Feb. 14, 1989; U.S. Pat. No. 4,770,815, issued Sep. 13, 1989; U.S. Pat. No. 5,035,814, issued Jul. 30, 1991; U.S. Pat. No. 5,047,165, issued Sep. 10, 1991; U.S. Pat. No. 5,419,853, issued May 30, 1995; U.S. Pat. No 5,294,365, issued Mar. 15, 1994; GB Application No. 2,144,763, published Mar. 13, 1985; GB Application No. 2,154,599, published Sep. 9, 1985; WO Application No. 9,296,150, published Apr. 16, 1992; WO 94/22800, published Oct. 13, 1994, WO 93/04153, published Mar. 4, 1993, WO 97/22651, published Jun. 26, 1997, EP Application No. 342,177, published Nov. 15, 1989 and xe2x80x9cGlyceryl Bisether Sulfates. 1: Improved Synthesisxe2x80x9d Brian D. Condon; Journal Of the American Chemical Society, Vol. 71, no. 7 (July 1994).
SUMMARY OF THE INVENTION
This need is met by the present invention wherein a process for preparing a low-foaming nonionic surfactant is provided. The low-foaming nonionic surfactant, either alone or in combination with other surfactants, provides improved spotting and filming performance as well as improved cleaning performance on greasy soils and suds or foam suppression in certain applications. While not wishing to be bound by theory, it is believed the alcohol surfactants of the present invention deliver superior spotting and filming benefits via improved sheeting action. As for improved cleaning performance on greasy soils, such benefits are shown when the alcohol surfactants of the present invention are employed in conjunction with a high cloud point nonionic surfactant as disclosed in detail herein. Lastly, the alcohol surfactants of the present invention may also act to reduce the suds or foaming associated with food soils or various other cleaning agents and allow the use of soluble surfactants, which are high sudsing, such as amine oxides.
In accordance with a first aspect of the present invention, a process for preparing an ether-capped poly(oxyalkylated) alcohol surfactant is provided. The alcohol has the formula:
R1O[CH2CH(R3)O]xCH2CH(OH)CH2OR2
wherein R1 and R2 are linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from about 1 to about 30 carbon atoms; R3 is H, or a linear aliphatic hydrocarbon radical having from about 1 to about 4 carbon atoms; x is an integer having an average value from 1 to about 30, wherein when x is 2 or greater, R3 may be the same or different, independently H, or C1 to C4 in any given molecule, further wherein when x is 15 or greater and R3 is H and methyl, at least four of R3 are methyl, further wherein when x is 15 or greater and R3 includes H and from 1 to 3 methyl groups, then at least one R3 is ethyl, propyl or butyl, further wherein R2 can optionally be alkoxylated, wherein said alkoxy is selected from ethoxy, propoxy, butyloxy and mixtures thereof. The process comprises the steps of:
(a) providing a glycidyl ether having the formula: 
xe2x80x83wherein R2 is defined as above;
(b) providing an ethoxylated alcohol having the formula: 
xe2x80x83wherein R1, R3 and x are defined as above; and
(c) reacting the glycidyl ether with the ethoxylated alcohol to form the surfactant.
R1 and R2 are preferably a linear or branched, saturated or unsaturated, aliphatic hydrocarbon radical having from about 6 to about 22 carbon atoms and x is an integer having an average value of from about 6 to about 15.
The step of reacting of glycidyl ether with ethoxylated alcohol may be conducted in the presence of a catalyst such as a mineral acid, Lewis acid or mixtures thereof. Preferably, the catalyst is a Lewis acid selected from the group consisting of TiCl4, Ti(OiPr)4, ZnCl4, SnCl4, AlCl3, BF3xe2x80x94OEt2 and mixtures thereof with SnCl4being the most preferred. The step of reacting the glycidyl ether with the ethoxylated alcohol is preferably conducted at a temperature of from about 50xc2x0 C. to about 95xc2x0 C. with 60xc2x0 C. to about 80xc2x0 C. even more preferred.
The step of providing the glycidyl ether may further comprises the step of reacting a linear aliphatic or aromatic alcohol having the formula R2OH and an epoxide having the formula: 
wherein R2 is defined as above and X is a leaving group. This reaction may also be conducted in the presence of a catalyst as defined above. The catalyst is typically employed at levels about 0.1 mol % to about 2.0 mol % and is preferably conducted in the absence of a solvent at temperatures of from about 40xc2x0 C. to about 90xc2x0 C.
As already noted, the surfactants has advantages, including superior spotting and filming reduction benefits as well as excellent greasy soil removal, good dishcare, suds suppression and good overall cleaning.
Accordingly, it is an aspect of the present invention to provide a process for producing a low-foaming nonionic surfactant having superior spotting and filming reduction benefits as well as excellent greasy soil removal, good dishcare, suds suppression and good overall cleaning. It a further aspect of the present invention to provide a process for producing an ether-capped poly(oxyalkylated) alcohol surfactant. These and other aspects, features and advantages will be apparent from the following description and the appended claims.
All parts, percentages and ratios used herein are expressed as percent weight unless otherwise specified. All documents cited are, in relevant part, incorporated herein by reference.
Once again, the present invention is directed toward a process for producing a low-foaming nonionic surfactant for use in detergent compositions.
The novel surfactants of the present invention comprise ether-capped poly(oxyalkylated) alcohols having the formula:
R1O[CH2CH(R3)O]x[CH2]kCH(OH)[CH2]jOR2
wherein R1 and R2 are linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from about 1 to about 30 carbon atoms; R3 is H, or a linear aliphatic hydrocarbon radical having from about 1 to about 4 carbon atoms; x is an integer having an average value from 1 to about 30, wherein when x is 2 or greater R3 may be the same or different and k and j are integers having an average value of from about 1 to about 12, and more preferably 1 to about 5, further wherein when x is 15 or greater and R3 is H and methyl, at least four of R3 are methyl, further wherein when x is 15 or greater and R3 includes H and from 1 to 3 methyl groups, then at least one R3 is ethyl, propyl or butyl, further wherein R2 can optionally be alkoxylated, wherein said alkoxy is selected from ethoxy, propoxy, butyloxy and mixtures thereof.
R1 and R2 are preferably linear or branched, saturated or unsaturated, aliphatic or aromatic hydrocarbon radicals having from about 6 to about 22 carbon atoms with about 8 to about 18 carbon atoms being most preferred. Additionally, R2 may be selected from hydrocarbon radicals which are ethoxylated, propoxylated and/or butoxylated. H or a linear aliphatic hydrocarbon radical having from about 1 to about 2 carbon atoms is most preferred for R3. Preferably, x is an integer having an average value of from about 1 to about 20, more preferably from about 6 to about 15.
As described above, when, in the preferred embodiments, and x is greater than 2, R3 may be the same or different. That is, R3 may vary between any of the alkyleneoxy units as described above. For instance, if x is 3, R3 may be selected to form ethyleneoxy(EO) or propyleneoxy(PO) and may vary in order of (EO)(PO)(EO), (EO)(EO)(PO); (EO)(EO)(EO); (PO)(EO)(PO); (PO)(PO)(EO) and (PO)(PO)(PO). Of course, the integer three is chosen for example only and the variation may be much larger with a higher integer value for x and include, for example, multiple (EO) units and a much small number of (PO) units. However, when x is 15 or greater and R3 is H and methyl, at least four of R3 are methyl, further wherein when x is 15 or greater and R3 includes H and from 1 to 3 methyl groups, then at least one R3 is ethyl, propyl or butyl.
Particularly preferred surfactants as described above include those that have a low cloud point of less than about 20xc2x0 C. These low cloud point surfactants may then be employed in conjunction with a high cloud point surfactant as described in detail below for superior grease cleaning benefits.
Most preferred according to the present invention are those surfactants wherein k is 1 and j is 1 so that the surfactants have the formula:
R1O[CH2CH(R3)O]xCH2CH(OH)CH2OR2
where R1, R2 and R3 are defined as above and x is an integer with an average value of from about 1 to about 30, preferably from about 1 to about 20, and even more preferably from about 6 to about 18. Most preferred are surfactants wherein R1 and R2 range from about 9 to about 15, R3 is H forming ethyleneoxy and x ranges from about 6 to about 15.
Basically, the alcohol surfactants of the present invention comprise three general components, namely a linear or branched alcohol, an alkylene oxide and an alkyl ether end cap. The alkyl ether end cap and the alcohol serve as a hydrophobic, oil-soluble portion of the molecule while the alkylene oxide group forms the hydrophilic, water-soluble portion of the molecule.
It has been surprisingly discovered in accordance with the present invention that significant improvements in spotting and filming characteristics and, when used in conjunction with high cloud point surfactants, in the removal of greasy soils relative to conventional surfactants, are provided via the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention.
It has been surprisingly discovered that the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention in addition to delivering superior cleaning benefits also provide good suds control. This suds control can be clearly seen in the presence of high sudsing surfactants, such as amine oxides, or in the presence of high sudsing soils, such as proteinaceous or egg soils.
Generally speaking, the ether-capped poly(oxyalkylene) alcohol surfactants of the present invention may be produced by reacting an aliphatic alcohol with an epoxide to form an ether which is then reacted with a base to form a second epoxide. The second epoxide is then reacted with an alkoxylated alcohol to form the novel compounds of the present invention.
The process comprises the first step of providing a glycidyl ether having the formula: 
where R2 is defined as above. Various glycidyl ethers are available from a number of commercial sources including the Aldrich Chemical Company. Alternatively, the glycidyl ether may be formed from the reaction of a linear or branched, aliphatic or aromatic alcohol of the formula R2OH where R2 is defined as above and an epoxide of the formula: 
where X is a suitable leaving group. While a number of leaving groups may be employed in the present invention, X is preferably selected from the group consisting of halides including chloride, bromide, and iodide, tosylate, mesylate and brosylate, with chloride and bromide being even more preferred with chloride being the most preferred (e.g. epichlorohydrin).
The linear or branched alcohol and the epoxide are preferably reacted at ratios ranging from about 0.5 equivalents alcohol to 2.5 equivalents epoxide with 0.95 equivalents alcohol to 1.05 equivalents epoxide more typical under acidic conditions for catalysis purposes. Acids which may be employed as catalyst include mineral acids, including but not limited to H2SO4 and H3PO4 and Lewis acids including, but not limited to, TiCl4, Ti(OiPr)4, ZnCl4, SnCl4, AlCl3, and BF3xe2x80x94OEt2. Preferred catalysts include the Lewis acids with SnCl4 and BF3xe2x80x94OEt2 being the most preferred. The catalysts are preferably employed at amounts of about 0.1 mol % to about 2.0 mol % with 0.2 mol % to about 1.0 mol % being more typical.
While the reaction may be conducted in the presence of a suitable solvent such as benzene, toluene, dichloromethane, tetrahydrofuran, diethylether, methyl tert-butylether or the like, the reaction is preferably conducted neat or in the absence of solvent. Lastly, the reaction is conducted at temperatures preferably ranging from about 40xc2x0 C. to about 90xc2x0 C., more preferably from about 50xc2x0 C. to about 80xc2x0 C.
Upon completion of the reaction, the mixture is treated with a basic material to form the glycidyl ether. The basic material is preferably a strong base such as a hydroxide. Preferred hydroxides include alkali metal hydroxides with sodium being the typical choice. However, one of ordinary skill in the art will recognize that other basic materials may also be employed. The basic material is preferably added at levels of from about 0.5 equivalents to about 2.5 equivalents, with 0.95 equivalents to 2.0 equivalents being more preferred.
The product glycidyl ether may then be collected after optional filtration, drying and distillation according to the methods well-known in the art. However there is no need to isolate/purify the product especially when symmetrical ethoxylated alcohol are to be formed.
To form the surfactant, an ethoxylated alcohol having the formula: 
wherein R1 and x are defined as before in an amount of from about 0.80 to about 2.0 equivalents is combined with a catalyst as described hereinbefore and heated to a temperature ranging from about 50xc2x0 C. to about 95xc2x0 C. and more preferably from about 60xc2x0 C. to about 80xc2x0 C. The glycidyl ether is then added to the mixture and reacted for from about 0.5 hours to about 30 hours, more preferably from about 1 hour to about 24 hours.
The ether-capped poly(oxyalkylated) alcohol surfactant product is then collect by means common in the art such as filtration. If desired, the surfactant may be further treated by stripping, distillation or various other means before use. The surfactants made the process disclosed herein may contain related impurities which will not adversely affect performance.